Shane Richmond is Head of Technology (Editorial) for Telegraph Media Group. He first joined the Telegraph in 1998 and has been Online News Editor and Communities Editor. He writes about all kinds of technology but especially Apple, iOS, ebooks and ereaders, and digital media.

Apple said: "There are more than 40 full-time trained reviewers, and at least two different reviewers study each application so that the review process is applied uniformly. [...] We receive about 8,500 new applications and updates every week, and roughly 20 per cent of them are not approved as originally submitted."

Assuming that all 40 reviewers work a five-day week then they're reviewing around 10 apps per hour. Apple's App Store review process has been much-criticised recently but with those numbers it's a wonder it functions at all.

Apple said it hadn't rejected Google Voice but was "studying" it because "it appears to alter the iPhone’s distinctive user experience by replacing the iPhone’s core mobile telephone functionality and Apple user interface with its own user interface for telephone calls, text messaging and voicemail".

However, as John Gruber points out on his blog: "The problem with this explanation is that it doesn’t explain (a) why the three other Google Voice-related apps — which were not by Google, and which were already in the App Store — were removed from the App Store; and (b) why other apps which deal with SMS and phone dialing are allowed."

The inconsistencies in Apple's explanation were also questioned by 9 to 5 Mac: "Strangely, applications like Skype also do many of these things and frankly more. In fact, Skype's dialer can easily be confused with the iPhone's built-in version. It has its own voicemail and SMS as well."

If Apple wants to avoid apps that alter the iPhone's "distinctive user experience" does that mean Spotify's app will be rejected? Apple says that "95 per cent of applications are approved within 14 days of their submission" but the Spotify app has been in the system for more than a month.

Despite its very long letter, Apple hasn't yet answered all the questions about the App Store.